Neisseria gonorrhoeae is currently a major cause of sexually transmitted disease worldwide. Despite effective antibiotic therapies, the development of immunoprophylactic measures is desirable. Essential to such development is a thorough understanding of the surface structures of the gonococcus, especially those structures that are conserved among diverse strains and thus may be potential targets for immunopropohylactic efforts. Most studies of gonococcal surfaces seem to have concentrated on the diversity of the organism. It is the aim of this proposal to examine three species of gonococcal surface proteins that show conservation of protein structure and antigenic determinants; specifically these are OMP-MC, protein III and proteins II. These proteins share the common features of being exposed on the cell surface, being antigenic and comprising a significant portion of the outer membrane protein mass. Particular emphasis will be placed on characterizing OMP-MC, since relatively little is known of this complex. Specific studies will determine the isoelectric point, subunit composition, fine structure surface exposure, in vivo organization and membrane environment of OMP-MC. Polyclonal and monoclonal antibodies against these three protein species will be produced and tested for their direct effects on cells and for their complement-mediated bactericidal and opsonic potentials. Human antibody responses directed against these proteins will be assessed by probing immunoelectrophoretic transfers of outer membrane proteins with sera from patients with various forms of gonococcal disease. Variations in the surface exposure and membrane environment of these proteins among diverse gonococcal strains will be examined, utilizing intact organisms as well as shed membrane vesicles. Of particular interest will be the comparative study of DGI and non-DGI strains. Finally, the recovery of specific genetic mutants exhibiting altered protein expression will be attempted; such mutants should provide insights into the funciton of each protein species and their roles in the surface architecture of the organism.